Update web editor page

[ethanpalm]

This PR updates the Web Editor page.

Summary of changes:

• Update introduction to highlight value of using the web editor
• Move Web editor vs. CLI section to a subsection of the introduction since it is an evaluation people would make as part of determining if they'll read this whole page
• Give an opinion on why you'd choose each editor mode
• Move the component menu to a subsection of visual mode since it can't be used in source mode
• Remove available components section since this is clear from the product UI and it helps streamline the article
• Reorganize the procedural sections into ordered lists where appropriate and so that they follow the flow of making changes -> publishing
• Update markdown mode to source mode to match UI labels
• Change capitalization to web editor
• Improve alt text for images
• Remove passive voice